John Calvin on John 15:4

4. Abide in me. He again exhorts them to be earnest and careful in keeping the grace which they had received, for the carelessness of the flesh can never be sufficiently aroused. And, indeed, Christ has no other object in view than to keep us

as a hen keepeth her chickens under her wings, (Matthew 23:37)

lest our indifference should carry us away, and make us fly to our destruction. In order to prove that he did not begin the work of our salvation for the purpose of leaving it imperfect in the middle of the course, he promises that his Spirit will always be efficacious in us, if we do not prevent him. Abide in me, says he; for I am ready to abide in you And again, He who abideth in me beareth much fruit. By these words he declares that all who have a living root in him are fruit-bearing branches